Snap-action switch



w. H. WOOD SNAP-ACTION SWITCH iled sept. 9, 1954 July 24, 1956 WIW/'am H Woaag United States Patent O SNAP-ACTION SWITCH William H. Wood, Wesleyville, Pa., assignor to Generali Electric Company, a corporation of iorh Application September 9, 1954, Serial No. 454,944

3 Claims. (Cl. 20G- 18) This invention relates to snap switches, and more particularly to spring operated means for insuring positive snap-action of a pivoted contact carrying member between closed and open circuit positions.

In many switch applications, it is necessary that the switch contacts be separated by a snap action at such a high speed that arcing between the contacts will be reduced to a minimum. It is therefore desirable that means be provided to positively secure snap mechanisms in a switch until the spring operator is fully tensioned to move the switch contact-carrying member. lt is also desirable in a snap switch where arcing is a common hazard to have some positive means for forcibly separating the contacts which may have been welded together by excessive currents so as to prevent separation thereof by the operating spring.

Therefore, an object of this invention is to provide a simple and reliable means for forcibly separating the contacts in the event they are welded together, and for operating the contact carrying member in the event of failure of the operating spring.

Another object is to provide simple and reliable spring means for operating a pivoted contact member between closed and open circuit positions together with latching means for securing the contact carrying member in the closed or open position until a predetermined operating force has been built up in the spring after which the contact member is released for movement by the spring.

A further object is to provide a simple and reliable snap switch of the type that has a momentary contact member on the shaft which actuates the snap switch for resetting any circuit breakers or relays of the type that are common in heavy-duty switch applications.

Briefly stated, in carrying out this invention in one form, l provide a pivoted contact member which is normally secured by a latching bar in the open or a closed circuit position and which is moved from one position to the other by a rotatable operator connected thereto by a spring. The operator is provided with a cam which, after an initial rotation of the operator during which the spring is tensioned, moves the bar to release the contact member for snap movement to the other position, after which the locking bar secures the contact member. Also mounted on the shaft is positive operating means for engaging and moving the contact member upon continued movement of the operator in the event of contact welding or spring failure.

Further objects and advantages of this invention will. become apparent and this invention will be better understood from the following description referring to the accompanying drawings in which:

Fig. 1 is a top view of a particular snap switch illustrating this invention;

Fig. 2 is an end view of the switch shown in Fig. 1;

Fig. 3 is a side view, partially broken away, of the switch shown in Fig. l;

Fig. 4 is an end view, lpartially broken away, of a 2,756,292 Patented July 24, 1956 switch with the cam rotated to the point where the bar is fully retracted; and

Fig. 5 is a simplified circuit showing the reset feature of the switch.

Referring now to the drawings, I have shown therein a preferred embodiment of my switch, having a mounting or base member 1 which may be secured to any convenient surface.

The switch base member 1 supports the rotatable shaft operator 2 and the operating handle 3 secured thereto in some type of bearings shown as the sleeves 4. The disc cams 5 and 6 are secured to the shaft 2 by some convenient means such as keys, rivets or roll pins. The rod 7 is connected between these cams and atixed to them to engage and move either end of a helical spring 8 surrounding the shaft 2 when the shaft 2 is rotated, thereby to energize the spring.

In order that this spring force may be applied to the shorting bars 9, the pivotable contact means, shown as member l@ which supports the shorting bars 9 is secured to the base or bight portion of a U-shaped support member 11 which is provided with apertures through the center of its bifurcations so that it may be pivotally mounted on sleeve bearings 12. The support member 11 has a rod 13 secured between the ends of its bifurcations to be operatively engaged by the end of the spring 8 that is not engaged by rod 7.

However, it is desired to prevent the movement of the movable support member 11 until the spring 8 is tensioned a predetermined amount. A rectangular locking bar 14 is positioned within the longitudinal slot 15 through the center of the bight of the support member 11. The springs 1S and 19 force the ends of the bar 14 from the contact member 1t? into the stationary rectangular slots 16 and 17 cut in the base member 1. Rotation of members 9, 10 and 11 is prevented as long as the bar 14 remains in the fixed slots .lo and 17.

Referring now to Fig. 4, the shaft 2 has been rotated a predetermined amount so that the sloping cam grooves 5a and 6a are no longer centered under the bar 14. The bar 14 is retracted from stationary slots 16 and 17 by the cams 5 and 6 against the pressure of the springs 18 and 19, freeing the support member 11 to rotate in response to the pressure on the rod 13 applied by the tension of spring S when the rod 7 is moved by the rotation of the rotatable shaft 2. To insure a positive drive, pins 20 and 21 are secured to the shaft, specifically to the cams 5 and 6. lt should be noted in Fig. 4 that the pin 21 has approached the rod 13. lf the contact member 10 should be unmoved by tension in the spring 8 after the bar 14 has been retracted, the pin 21 upon a slight further movement clockwise will apply positive pressure from the shaft 2 through the cam 5 to the rod 13 forcing the release of the contact member 10 so that it may respond to the tension of spring 3. Even if the spring S were broken by misuse or excessive use, the pin 21 would directly and positively drive the contacts to the desired position. Similarly the pin 2t) will positively drive the contact member 16 to open the switch if the contacts 22 and 23 should be welded shut by excessive currents or arcing.

The shorting bars 9 are resiliently mounted on the contact member 10 by means of the pins 24 and the springs 25. Movement of the shorting bars 9 relative to the Contact member 10 will slightly shorten the distance between the center of the operating shaft 2 and the contact 22 giving a wiping action between the engaging contacts 22 and 23 whenever a connection is made or broken. This wiping action has been found to be desirable in high current switches. Whenever the contact is completed, the end springs 2S are somewhat compressed by the counterclockwise movement (Fig. 4) of shorting bars 9 relative to contact member 10. This allows the velocity .oi the Contact ,to .be ,increased appresably without .damage because of the slight momentum of the shorting bar 9 and the contact 22. Similarly, 'the slight compression of the spring 2'5 allows-the Acontact member 10 to pickup con siderable momentum before disconnecting the contact 22 from Vthe contact 23. This pin 24 and spring 25 also assure the maintenance of a contact when the contacts 22 and 23 have worn.

yIn heavy fduty applications it is desirable to securely attach another contact membersuch as 26 to the shaft 2, so that shorting bar 27 carried thereby may be moved to close -a circuit through contacts 28. Such anvapplication, as `shown in Fig. 5, is of utility where `heavy duty circuit 'breakers such as 29 for protecting the system Vmust be closed by a relay or similar electrical means. Contacts I28 are connected in a reset relay circuit that does not carry as much current as contacts of the snap switch, so that a slow-acting switch is `feasible from the standpoint of arcing. Shorting bar 27 shorts contacts 28 to energize the coil 31 to reclose the circuit breaker 29 only when handle 3 is rotated more than shown in Fig. 4 to overcome Vthe tension of spring 30 as well as the tension created by -the spring 8. The operator will not short the contacts '28 by mistake, for spring 30 is designed to be rather stiff.

Referring to Fig. l, the de-energized position of the switch is shown and shorting bar 27 lies behind the shorting -bars 9, and will not ordinarily close its respective circuit when the circuits of shorting bars 9 are closed. To operate the reset shorting bar 27 the shaft must be rotated clockwise past the position shown in Fig. 4, which yillustrates the clockwise snap action beginning. When the contact member 10 has moved to the new position shown by the dash lines 32 contact is made with the snap por- 4tion of the switch connecting shorting bar 9 to contacts '23. Then the shaft may be rotated somewhat `further to bring the shorting bar 27 into energy contact with the contacts 28 and thereby reclose the circuit breaker 29, or

makewhatever connection is necessary for the particular application.

When it is desired to move the switch shorting bar 9 to the open circuit position, the operator merely rotates -the handle 3 in the counterclockwise direction as shown in Fig. 4 until the cam grooves 5a and 6a of the cams 5 and f6 retract the rectangular locking bar 14 suiciently to clear stationary slots 33 and 34 allowing the Contact member 410 to return to the position shown in Fig. l in which it is stoppedby the bar 14 forced into the slots 16 and 17 by springs lrand 19. The pin '20 may be utilized to insure the desired rotation of contact member 10 if the helical spring 8 is inoperative because of spring failure or contact welding.

Should it be found desirable, this particular construc- `tion couldhave another set of ystationary contacts (not shown) positioned so that the locking bar 14 and the slots35 and 36 may be utilized. The switch would then be a double-throw snap switch. More than two shorting bars could be mounted on the contact member 10,

'In'summary of the operation, referring to Fig. 3, the handle 3 will be rotated so that the shaft 2 causes the cams and 6 to rotate, thus reti-,acting the bar '14 from the slots l16 and 17 and applying pressure through the rod 7 to tension one end of the concentric helical spring 8. The. otherv en d of the spring 8, in turn, applies pressure to the rod 13, which is mechanically connected to the contact member throughmovable support member 11. Memberll is mounted on the bearings 12 concentric with the springs, and when theshaft 2 has been rotated Suthciently to cause the slopinggrooves 5a and 6a of the cams v5 ando yto retract the bar14 from the slots 16 and 17,

the, tension ,of spring 8 or the forceV ofpin 2i) or 21 causes .the pntact memberlllto follow the rotation of theshaft 2, Whenthishappeps, thebv'lr is againpositioned @Ver next setnof slots 33 and 34 or 3S and 36.

To reclose a relay or circuit breaker 29, the shaft V2 may be further rotated to connect the contacts 28 by the shorting bar 27. The shaft is then released and returned by spring 30 to disconnect the shorting bar 27 from contacts 28.

While I have shown and described particular embodiments of my invention, it will be understood, of course, that I do not wish to be limited thereto since many modifications may be made. I therefore contemplate by the appended claims to coverany such modifications as may fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. A heavy duty snap-action switch comprising a base member having bearings therein, a rotatable shaft mounted in said bearings, a pivotable support member provided with a slot and mounted concentrically on said shaft, a contact member mounted on said support member, a rectangular locking bar resiliently mounted in said slot for .preventing movement of said contact member, said locking bar being resiliently held yparallel to said shaft in stationary slots in said base, a disc cam secured to said shaft for retracting said locking bar from said slots when said shaft is rotated a predetermined amount, a rod mounted on said disc cam parallel to said shaft, helicalspring positioned on said shaft having its ends vextending fromsaid shaft to be alternately engaged by `said rod, means for operably connecting said spring to said support member for forcing said contact member to follow said shaft rotation, a pin rigidly secured to said disc cam extending from said disc cam to contact and positively drive said support member when said spring fails to move said contact member after said shaft has :been rotated said `predetermined amount, and another contact member rigidly secured to said shaft to provide a momentary contact when the shaft is rotated beyond .the amount necessary to fully retract said locking bar.

2. A heavy duty snap-action switch comprisinga base vmember having bearings therein,ra rotatable shaft mounted insaid bearings, a U-shaped support member having apertures in the bifurcations thereof for `pivotally mounting said support member on said shaft, a contact member rigidlymounted on the bight of said support member, portions of the bifurcations and the bight of said support member being provided with a slot extending longitudinally therethrough parallel to the axis of said shaft, a rectangular locking `bar positioned in said slot with its ends extending beyond said bifurcations, spring means for biasing said locking bar toward said shaft, said base being provided with a pair of stationary rectangular slots in opposite sides ofrsaid support member into which said ends of said Alocking bar are moved by said spring means to lock said Contact member, cam means secured to said shaft having sloping grooves thereon normally positioned under said locking bar to allow movement of said locking bar into saidslots, and spring means vsecured between said shaft and said support member. to force said support member to follow the rotation of said shaft when said shaft is rotated ya predeterm,ined vamount sufficient for said cam ymeans to retract said locking bar from said stationary Sl0ts.

3. A snapaction switch comprising a base provided with bearings, `a rotatable shaft mounted in said bearings, a pivotal contact means rotatably mounted on said shaft, locking means connected between said base Vand said contact means for preventing movement of said contact means, a disc cam secured to said shaft in a plane perpendicular to the axis of said shaft, said cam having an irregular outer surface for engaging and retracting said locking means from its locked position when said shaft and said cam are rotated a predetermined amount, a helical spring surrounding a portion of said shaft and having one end mechanically connected to said shaftand .the other, .end extending-therefrom to engagesaid Contact means for forcing said'contact means to follow rotation of References Cited in the file of this patent UNITED STATES PATENTS Reamer Dec. 3, 1935 

